server+discovery: send channel updates to remote peers reliably

In this commit, we also allow channel updates for our channels to be
sent reliably to our channel counterparty. This is especially crucial
for private channels, since they're not announced, in order to ensure
each party can receive funds from the other side.

server.go

@@ -593,14 +593,11 @@ func newServer(listenAddrs []net.Addr, chanDB *channeldb.DB, cc *chainControl,
 	}
 
 	s.authGossiper = discovery.New(discovery.Config{
-		Router:     s.chanRouter,
-		Notifier:   s.cc.chainNotifier,
-		ChainHash:  *activeNetParams.GenesisHash,
-		Broadcast:  s.BroadcastMessage,
-		ChanSeries: chanSeries,
-		FindPeer: func(pub *btcec.PublicKey) (lnpeer.Peer, error) {
-			return s.FindPeer(pub)
-		},
+		Router:            s.chanRouter,
+		Notifier:          s.cc.chainNotifier,
+		ChainHash:         *activeNetParams.GenesisHash,
+		Broadcast:         s.BroadcastMessage,
+		ChanSeries:        chanSeries,
 		NotifyWhenOnline:  s.NotifyWhenOnline,
 		NotifyWhenOffline: s.NotifyWhenOffline,
 		ProofMatureDelta:  0,